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Improve quality of Karma Depth AOV?


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My depth passes are always crunchy coming out of Solaris, and when there is a close FG object against a very distant BG this leads to some brutal fringing when defocusing (in post). I've tried both XPU and CPU, cranking the global samples significantly, and that doesn't change. What do I need to do to get good depth passes?

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Under the view tab on the Solaris camera, it's called the clip range. The far value defaults to 1 million meters. This means all 0-1 depth information is remapped from 1-1,000,000. Find the distance of the farthest element in your scene and set the far range to that value. This might improve the overall resolution of the depth map.

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The far clip was already pretty reduced, that didn't help. (Thanks, though.)

 

I found the problem spot: The background in this is to be added in post, so there is no background in the project. The chunkiness of the depth pass (which I understand is just the nature of the beast of depth passes) is not as much a problem when there are objects in front of objects, but any the depth pass edges of any object in front of the transparent non-background don't match the chunkiness of those in front of other objects, which gives it a weird bad-light-wrap-looking fringing. I think the solution would be to have an actual object/white wall in the distance, but it would only be able to show in the depth pass, not in any other AOVs. (When I tried putting a grid there it worked great, but then I had a grid in my scene which didn't help.) Is there a way to have an object in Karma that ONLY shows up in the depth pass? It seems like once something is invisible to primary rays it's also invisible in the depth pass.

 

The attached image shows the problem area where the fringe becomes very visible but doesn't present a problem when there's a background. (This is zoomed in 800%, so chunkiness is not shown to scale)

Capture.PNG

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Increased resolution or deep rendering would have added a whole lot of rendering time and/or disk space, so I had ruled those out pretty early. Thanks for the tips, though!

What fixed it (thanks to feedback from the CGWiki Discord) was placing a far "wall" with render geometry settings set to primary only and the holdout mode set to "background". That way the harsh edges (which is really just pixels carring single values) didn't just stop where the background ended, as there was always a background.

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